1. Field of the Invention
The invention pertains to optical systems for detecting angular displacement and more particularly to a novel device utilizing a gaseous discharge lamp and a photodetector to measure angular displacement.
2. Description of the Prior Art
Optical systems for measuring angular displacement presently in use and in particular, those systems used as pick-offs for gyroscopic instruments, have succeeded in resolving the limitations inherent in the more conventional systems. Specifically, conventional pick-offs, synchros, or the like, add additional weight to the system and produce a coupling or counter torque which introduces error and further necessitates the use of additional energy to compensate for the increased drag on the gimbal system. Prior art optical systems suffer from other limitations. In particular, prior art optical systems for measuring angular displacement in gyroscopic instruments are composed of numerous parts which require extensive and intricate machining in their manufacture and assembly thereby adding substantial cost and production time to the manufacture of the gyroscopic instrument. For example, see U.S. Pat. No. 3,313,161 entitled "Means for Measuring Relative Angular Displacement", U.S. Pat. No. 3,422,686 entitled "Optical Pick-Off Means for Deriving Signals Indicative of Deviation of Rotor Pole from Spin Axis" and U.S. Pat. No. 3,813,949 entitled "Light Actuated Solid State Pick-Off."
It is apparent, then, that a device is needed to measure angular displacement which is reliable, economical, and not subject to the limitations indicated above.